Stable breaking-in oil



Patented Sept. 22, 1942 s'mnm BREAKING-IN on.

Peter J. Gaylor, Union, and Emile L. Baldeachwieler, Craniord, N. 3., assiznors to Standard Oil Development Company, a corporation oi.

Delaware No Drawing. Application November 30, 1940, Serial No. 367,952

11 Claims.

This application is a continuation-in-part of our application, Stabilized lubricating oils, Serial No. 124,246, filed February 5, 1937.

The present invention relates to an improved oil composition and more specifically to a mineral oil composition of a type showing little or no corrosive properties on various metals or alloys with which it is brought in contact. The compositionwill be more fully understood from the following description:

It has been customary for some time to compound mineral oils with fatty oils or organic esters of fatty acids. These materials are frequently corrosive to metal bearings, containers, guides and the like, with which the oil is brought into contact, whether the metal be of iron, aluminum, lead, copper, cadmium, silver, or alloys such as steel, Babbitt, bearing bronzes, brass and the like. Such bearing metals generally range in electromotive force values from aluminum to platinum. It has also been found that certain unblended mineral oils such as lubricating oils of SAE to 50 viscosity, which have been highly refined, are likewise somewhat corrosive, especially at high temperature conditions. The corrosion is most severe when the newer type of alloy bearings containing copper-lead or cadmium-silver combinations are employed. Such corrosion is usually manifested when the oils are used in the presence of air, but even in cases where air is apparently absent, the oils are corrosive, resulting in the leaching out oi one or more component metals causing a honeycombing and resultant weakening of the bearing surface. This maybe due to dissolved air, but in any case it is naturally desirable to produce oils which are not corrosive under these conditions, and it has been found that certain materials can be added to such oils to prevent, or at least to largely eliminate, the corrosive action on various metal compounds. Although the action of these materials is not fully understood, certain combinations oi the addition agents are extreme- 1y valuable for the purpose at hand.

The first constituent of the present composition is of course an oil. This may be a straight mineral oil of the highly refined variety, for example prepared by a heavy extraction with solvents or by the action of concentrated or fuming sulfuric acid. It is usually found that the more highly refined the oil, the more corrosive it becomes. The oil may be of the transformer or of the lubricating, penetrating, flushing or slushing type; it may contain either distilled or residual oil and some solid hydrocarbons, such as waxes, or blends thereof. As noted above, such oils may be compounded with fatty oils or fatty compounds such as fatty esters, e. g., the mono or dihydric alcohol esters of or,- ganic acids, high boiling organic acids such as oleic, stearic, naphthenic, hydroxy stearic, chlor stearic and those prepared by oxidation of oils, waxes and other hydrocarbons. These materials may be added for any purpose such as to increase oiliness or for other reasons, but the addition of such materials almost invariably increases the corrosive tendencies of the oil, particularly with respect to the bearing metals.

The second ingredient making up the oil composition consists of a small amount of an oilsoluble ester of an acid which forms an oil-insoluble salt of the metal or metals with which it is to be brought in contact, that is to say, if the oil is to be brought in contact with a bearing containing lead, the ester should be one whose acid (upon decomposition of the ester) forms an oil-insoluble lead salt. There are many difierent esters which may be used, but it is preferred to use polybasic, as for example dibasic acid esters such as nitrates, tartrates, oxalates, succinates, and the like. Monobasic acid esters may, however, be used in place of the aforementioned dibasic acid esters, but these monobasic acid esters should be chosen carefully since many of the monobasic acid esters form oil-soluble salts. The suitability of a given ester is determined by the substantial insolubility of the salts of the acids in oil and the solubility in oil of the ester itself. Thus, for example, if one were to question whether or not a given ester were usable, the ,test would he, first, to detenmine the solubility of the ester itself in oil, and then to test the solubility of the salts of the acid of the ester in oil and if the latter are insoluble in oil, the ester may be used in our present invention. In other words, the ester itself must be oil-soluble but the salts, for instance, the lead, iron, etc., salts of the acid component of the ester must be oil-insoluble in order to be operative in'our precess. soluble we mean its solubility substantially not more than that of the salt formed by the action of butyl tartrate in 0.5% solution in an SAE 30 (Society of Automotive Engineers) Pennsylvania oil at a temperature of fi10 F.

In using the esters it is preferred to use the monohydric alcohols, from methyl to amyl or hexyl inclusive, but aryl alcohols and other laydroxy compounds may be used in many cases. The amount of the said ester may vary-consider- By the term inably, depending on the particular agent used and degree of protection desired, but in many instances it has been found that as little as 0.01% is sufiicient. Usually, however, about 0.1% to 0.5% is preferred, but in some instances as much as 1% to 5% is desirable.

The thirdingredient of the present composition is from the class of soluble amines either aliphatic or aromatic, although the latter are preferred, particularly those having more than six carbon atoms, aniline being much less effective than the higher amines. The amines may be of the primary, secondary or tertiary type, and include the toluidines, xylidines and particularly alkylated and substituted polycyclic amines, such as benzidines, which latter, are particularly effective. These substituted amines, such as alkylated or arylated anilines are especially efiective.

As stated above, the explanation of the desirable result obtained by the proper combination of the three ingredients is not fully understood, particularly with respect to the amines, but it is nevertheless the fact that the combination of these ingredients is much preferred to the use of either ingredient alone.

The test employed to determine the suitability of a, lubricating composition for continuous use in the presence of various bearing metals involves immersing a measured portion of the bearing in a bath of the lubricating composition maintained at 210 F., and samples of the oil are withdrawn at definite time intervals and tested for acidity, sapom'fication, appearance, etc. The bearing is likewise removed, washed with naphtha, and weighed to determine bearing loss, and likewise examined for appearance, etc. The following examples will illustrate these tests:

Example 1 A small piece of a copper-lead bearing of the type used in automobile engines is suspended in a bath (210 F.) of a solvent extracted lubrica ing oil (SAE 20 of Midcontinent origin) containing, as an oiliness agent, 2% of an isopropyl ester of the mixed acids boiling in the C16 and higher range, obtained by low temperature, atmospheric pressure catalytic oxidation of paraifin wax. The test was interrupted at intervals to determine the extent of the corrosion and the data given in the following table shows the result:

of tests comparable to that given in Example 1 are shown in the following table:

Loss Acidity.mg. Sap. Sample Hours KOH/gr.

Oil blend (Example l)+ 9.1% benzidine 322 27.8 8.7 24.7 Oil blend (Example l)+ 9.5% butyl tartmtc 296 ll. 5 0. 7 5. 9 01A bylegd (gxamplc l)+ .l cnzi ine Oil blend (Example l)+ 296 0.5% butyl tartrate From the above it will be seen that the combination of the two ingredients, 1. e., the benzidine and the ester, is much superior to either one alone.

Example 3 The same test was repeated except that butyl oxalate was substituted for the tartrate:

Sample Hours igggig ug- Shag.

Oil blend (Example l)+ 0.5% butyl oxalate l. 296 9. 2 3. 9 17. 6 Oil blend (Example l)+ 0.5% buyl oxalate 295 7 5 on blend (Example l)+ 0.1% benzidine The great decrease in acid and saponification numbers of the blended sample containing both ingredients should be noted.

I Example 4 A similar test was again repeated using amyl Steel ball bearing races were immersed in a lubricating oil blended with different agents and exposed to light in tightly stoppered bottles. In these cases no oiliness agent was added as in Example 1. After a period of about nineteen Io so! weeks, the bottles were opened and the samples Timehours w'eisght were examlned, both the oil and the metal, and

mg. the following was found:

Samples Condition of metal Condition of oil IIIIII:11111111111111:IIIII'IIIIIIII 56 296 Hydrocarbon oil Rust ra' th (1 M 322 62.7 al ne yyg 3,9 0 e I heavy de 0 011+0.l% toluid'me- Sligflfitdeposihwipes Heavy deposit.

0 98.51 y. Oil 0.1 bt'lt r t The curve is not exactly smooth, but there IS ,2;,,, u 3 at tmf gtgt'g t il nish. no doubt that the metal]- 15 rapldly corroded Wlth Q 1+ of each of Bright Clea-L out any indication of a decrease in rate. The oil at the end of the test had an acid number of 14.6 mg. KOH/grm. and saponification number of 4.6 mg. of KOH/grm.

Example 2 Separate samples of the same wax-ester blended oil as that employed in experiment 1 were blended with small proportions of benzidine and butyl tartrate separately, and the combination of the two last-named ingredients. The results the 2 above.

This oil is particularly useful in preparing anticorrosion compounds, slushing oils, and lubricants which must be kept in contact with bright metal parts such as needles, cutting edges and the like. The improvement due to the use of the combination of ingredients was, indeed, strikmg.

In the preceding examples, with the exception of Example 4, it will be noted that the acid was dibasic. A number of tests have also been car- Corrosion emperimentsContinued Blend Ni). 1+ Blend No. 1+ Blend No. 1+ Blend No. 1+ Blend Ne. 1+ 0.1% benzidlne+ 0.1% benzidine 0.1% benzidine 0.1% benzidine 0.1% benzidine 0.5% amyl valerete 0.1% ethyl valerate 0.5% ethyl valerate 0.1% methyl salicylate 0.5% methyl salicylate Time Cumulative Time Cumulative Time Cumulative Time Cumulative Time Cumulative loss in wt. loss in wt. loss 111 wt. loss in wt. loss in wt.

Daua Milligrams .Daue Milligrams Dal/a Milligrams Day/.1 Milligrams Days Milliarama 1 2. 5 1 0. 7 1 1. 9 1 0. 7 1 2. 3 2 3. 2 1. 4 2 2. 6 2 1. 2 2 2. 7 3 3. 2 3 l. 7 3 2. 9 3 l. 6 3 3. 2 4 3. 5 4 2. 3 4 3. l 4 2. 1 4 3. 3 5 3. 7 5 2. 4 5 3. 5 5 2. 3 5 3. 5 8 3. 8 8 2. 9 8 4. 0 8 2. 6 8 3. 9 9 3.8 9 3.1 9 4. 3 9 2. 7 9 4. 2 10 3. 9 10 3. 3 10 4. 6 10 2. 9 r 10 4. 4

At the conclusion of the tests set forth in the preceding page, the oil used was titrated to determine its neutralization and saponification values with the following results:

Neutralization and saponiflcatz'on values at the end of 10 days test Sa on. No. Neut. Sapon. Sample (1 due to (1) (1) added ester Blend No. 1 Essolube -14% oxidized wax acid esters 0.76 5, 36 Blend No. 1+0.1% ethyl propionate. 0. 14 3. 2A 0. 48 Blend No. 1+0.5% ethyl gropionete. 0. 14 2. 96 2. 4 Blend N0. 1+0.1% ethyl utyrate... 0. 11 3. 10 0. 43 Blend No. 1+0.5% ethyl butyrate. 0. 14 2. 96 2. 15 Blend No. l+0.1% amyl valerate. 0. 17 2. 96 0.30 Blend N0. 1+0.5% amyl valcrate..- 0. 17 3. 10 1. 50 Blend No. 1+0.1% ethyl valerate 0. 17 3. 24 0. 39 Blend No. 1+0.5% ethyl valerateuu 0. 14 3. 10 1. 94 Blend No. l+0.l% methyl salmylate. 0. 14 3. 10 0. 37 Blend No. 1+0.5% methyl salicylate. 0. 17 3. 10 1. 84 Blend No. 1 before starting tests 0. 14 3. 67

(1) Expressed in mgs. oi KOH/gm. of oil.

These latter titrations are interesting in showing the mechanism by which the benzidine and the ester probably prevent corrosion of the metal. For instance, the blend before starting the tests had a neutralization number of 0.14 and a saponification value of 3.67 (see last item in table). In the case of ethyl propionate the saponification value at the end of the test was 3.24, and of this amount 0.48 was due to the added ester, thus showing that there was no oxidation of the oil over a ten-day period. The other items in the table show similar results.

It is appreciated that many modifications of our invention may be made without departing from the pirit thereof.

We claim:

1. An oil composition for use in connection with metals corroded by oil, comprising a heavy mineral oil, a small quantity of an amine soluble in said oil and from about 0.01% to about' 5% of an oil-soluble ester of an acid which forms oil-insoluble salts with the metal in contact therewith.

2. An-oil composition for use in connection with metal corroded by oils, comprising a mineral oil, a soluble amine of more than six carbon atoms, and from about 0.01% to about 5% of an oil-soluble ester of a polybasic organic acid, which forms an oil-insoluble salt with said metal.

3. A composition according to claim 2 in which the ester is an ester of an aliphatic acid.

4.-. A composition according to claim 2 in which the ester is an ester of citric acid.

5. A composition according to claim 2 in which the ester is an ester of citric acid and the amine is benzidine.

6. A composition according to claim 2 in which the ester is an ester of tartaric acid and the amine is an alkylated polycyclic amine.

7. A composition according to claim 2 in which the ester is an acid of oxalic acid and the amine is benzidine.

8. Method of reducing the corrosion of bearing metals combinations exemplified by copperlead and cadmium silver, comprising contacting said bearings with a substantially non volatile oil containing 0.01% to 5% of a soluble substituted polycyclic aromatic amine, and 0.01% to 5% of an ester of an acid which forms salts with said metals, said salts being insoluble in said oil.

9. Method of reducing corrosion of steel surfaces, comprising contacting said surfaces with a. substantially non-volatile oil containing 0.01% to 5% of a soluble substituted polycyclic aromatic amine, and 0.01% to 5% of an ester of an acid which forms salts with said surfaces, said salts being insoluble in said oil.

10. A lubricant 'of low corrosion characteristics consisting essentially of a lubricating oil, a soluble amine and an oil-soluble ester of an acid, which forms insoluble heavy metal salts of said acid, both dissolved in said lubricating oil, the amount of ester based on the weight of the oil falling within the range of from about 0.01% to 5% 11. A lubricating oil containing a dissolved amine and a dissolved ester of an acid, which forms an insoluble heavy metal salt, the amount of ester based on the weight of the oil, falling within the range of from about 0.01% to 5%, the said oil-blend, possessing very low metallic corrosion characteristics.

PETER J. GAYLOR. EMILE L. BALDESCHWIELER. 

